1. Field of the Invention
The invention relates to a movement region prediction apparatus that predicts the movement region of a mobile body.
2. Description of the Related Art
A technology for predicting a travel course of a host vehicle and preventing the host vehicle from colliding with a mobile body, such as another vehicle or the like, which exists around the host vehicle in the predicted course has been developed. There also has been developed a technology for acquiring a target course that the host vehicle is to take in order to reach a destination, and for performing various travel controls or automatic driving in accordance with the target course. In this technology, too, it is important that the host vehicle travel while avoiding collision with surrounding mobile bodies. An apparatus described in Japanese Patent Application Publication No. 7-104062 (JP-A-7-104062) finds a predicted travel locus of a host vehicle and a predicted travel area thereof that has a predetermined extent on each of the two sides of the predicted travel locus on the basis of the yaw rate and the velocity of the host vehicle detected by sensors, and also finds a predicted travel locus of an obstacle (another vehicle or the like) and a predicted travel area thereof that has a predetermined extent on each of the two sides of the predicted travel locus on the basis of the position and the velocity of the obstacle that are detected by a radar. Furthermore, the apparatus calculates the point of the collision between the host vehicle and the obstacle or a point of proximity therebetween on the basis of the predicted travel area of the host vehicle and the predicted travel area of the obstacle, and determines the collision risk by calculating a target deceleration and a target reduced speed, and, if a risk of collision arises, performs a velocity control of the host vehicle according to the target deceleration and the target reduced speed.
In a common traffic environment, it is inevitable that a vehicle that is traveling in an abnormal manner and a vehicle that is traveling in a normal manner mingle, due to dozing at the wheel, drunk driving, or depending on the situation of compliance with traffic rules, etc. However, in the foregoing apparatuses, the area in which another vehicle moves is set uniformly for all vehicles. Therefore, if, assuming an abnormal vehicle, a broad area is set for each of the other vehicles around the host vehicle, the risk of collision of the host vehicle becomes high with respect to all the nearby vehicles (including normal vehicles), so that it becomes hard for the host vehicle to travel (see FIG. 2A). On the other hand, if, assuming a normal vehicle, a small area is set for each of the other vehicles around the host vehicle, the risk of collision of the host vehicle becomes low with respect to all the nearby vehicles, so that if an abnormal vehicle exists nearby, the safety of travel of the host vehicle declines (see FIG. 2B).